Electric brake.



wanna PATENTED SEPT. 4, 1906. F. L. SESSIONS.

ELECTRIC BRAKE.

APPLICATION FILED JAN. 17, 1905.

' 2 SHEETS-SHEET 2.

supporting-whee s 6.

UNITED STATES PATENT OFFICE.

FRANK L. SESSIONS, OF COLUMBUS, OHIO, ASSIGNOR TO JOSEPH A.

JEFFREY, OF COLUMBUS, OHIO.

ELECTRIC BRAKE.

Specification of Letters Patent.

Application filed 58111181! 17. 1905. Serial No. 241,524. i

This invention relates to an improvementin electromagnetically-operated brakes for cranes, elevators, or other machinery.

In the drawings for the sake of illustration 1 have shown one "of my electromagnetic brakes applied to a motor which is adapted to drive the traveling carriage of a hoisting and conveying apparatus.

Figure 1 is a side elevation of a carriage for a hoisting and conveyin apparatus having the driving-motor provi ed with an electroimprovement. Fig. -2 is a plan view of the said carriage. Fig. 3 is a diagrammatic view of the motor, brake, electromagnet controlling the operation of the brake, and the wiring of the e ectrical circuit.

1 represents as an entirety'a travelingcar riage which is adapted to move' back and forth upon the elevated trackway 2. The frame 3 of the carriage has mounted-in it the axles 4 and 5,-u on which are mounted the 7 is a motor secured indposition on the said frame adjacent to the a e 4 v 7 is a motor-pinion which is adapted'to engage with a gear-wheel 8, which is secured to the shaft 4, so that power may be applied from the motor-shaft for driving the axle 4 and advancing the carria 9 is a brake wheel or pu l e. ley rigidl secured to the shaft 4.

10 is a brake-ban ada ted to engage with the periphery of said w eel,

and 11 is a lever having. the ends of said band pivotally secured thereto, the lever being mounted on a stationary pivot or shaft 12, about the axis of which it is free to rock, so as to control the brake-band in the wellknown manner. From the outer end of the brake-lever is suspended a'weight 13, which is adapted to normally, hold the. brake-band 1n firm engagement with the periphery of the brake-wheel to axle 4.

14 represents a powerful electromagnet prevent the rotation of the 17 is a doubleole single-throw switch ar' ranged in the e ectrical circuit between the generator and the motor. 18 is a starting- OX or controller-of any well-known style It has three binding-posts, (indicated at 19, 20, and 21,) the wire 16 leading to the post 19 and bein secured therein. 22 is a conductor leading om.the binding-post 20 to one of the motor-brushes 23. 24 indicates a conductor leading from the motor-brush 25. to the negative pole of the switch 17. 21. is a conductor leading from the binding-post 19 to the binding-post 21. This conductor preferably has in its circuit electromagnet 2 1 a which is adapted to maintain the controller handle 18 in any position of adjustment as Patented Sept. 4, 1906.

long as the electromotive force of the motor remains above a certain value. 18 indicates a series of resistance-controllingcontacts arranged on the controller 18 in the well-known manner and adapted to be engaged by the switching-lever 18 to regulate the supply of the current to the motor; The electromagnet 14 is compound-wound,.1t having a coil 29 connected in series with the armature of the motor and a coil 30 connected directly This latter y means of a contact 2 31 on the controller-box, which is arranged across the current-supply line. connection I arrange to be engaged by the controller-lever 18 prior to its engagement with any of the series of contacts 18". is made through the shunt-winding of the In this manner the circuit brake-magnet 14 a little before the motorcircuit is completed. This will effect the lifting of the weight 13 and releasing of the brakeband 10 prior to the be tion of the armature-shaft 0 that it ma start free of the retarding action of the brake. After moving the controllerlever across part of the distance toward the right it leaves the brake shunt-coil contact 31, and the brakeis held in the off position,

inning of rotathe motor, so

or out of operation, by the action of the series coil 29 of the brake-magnet. If the armature-circuit in any Wise be opened, the

weight 13 will at once fall, clamping, the bra e-band to the brakepulley, slowing down or stopping the rotation of .the arma ture-shaft, causing the automatic startingbox to open, and thus preventlng any acc will consume very little energy and the shunt- Y coil, used only while the motor is being dent by runaway to the mechanism or conveyer controlled by the motor. I prefer to arrange the magnet 14 so that a small energizing-current in the series coil 29 will retain the brake in the off position after it has'once been drawn to thatposition by the energizin of' the magnet-core by the shunt-coil I he series coil 29 of the brake-magnet started, can be designed to exert a very strong'force for the short time it is in service without heating excessively and without wasting-much energy.

I am aware that heretofore it has been proposed to use electromagnets for actuating prevent the running away of the machinery,

which will be certam to occur unless there is a worm gear in the power transmitting mechanism. The magnet wound in series with the-armature of a shunt-wound or series wound motor will not lift the brake off until considerable current is flowing, thus throwing an unnecessa load upon the motor in starting.

tion as the direction'of rotation as a motor will cause the motor to run as a generator, exciting its shunt-field in the same direction as it was excited by the source of currentsupply when 0 crating as a motor, and con- 'sequently if t ere is any tendency of the mechanism controlled by the said motor to run awa it will drive the armature-shaft in such irection so as to develop a sufficient electromotive force to keep till: ex-

ra e om emg cited and to prevent the ap lied. 1 c

n my construction while the motor is a shunt-wound one andthe ma et-coil 30'is in multiple with the motoreld it will be noted that the shunt-coil 30 is not in series with the field when the motor is running normally,-as it is cut out after it has performed its-purpose of excitin he magnet 14 soasto lift the weight 13. other words, should With t e shunt-motor the rotation of the armature-shaft in the same direcbrake-band the motor start to run as a generator, the coil 29 of'the electromagnet bein -in' series wlth the armature-of the motor, t e direction of current throughth e coil would change and whenever the motor changes to become "a I generator or when operatin as a generator it a ain becomes a motor t ebrake will be no unusual speed "can be. attained the apparatus. I I

In startin the driving-motor the operator will throw t e controlling-lever over ,to the end of the contact, which completes the. circuit-through the shunt-windin of-the electromagnet, and will there hol it untiltheconveyer or other apparatus has, attained .sufiicient speed and oad to require retard-,

ing. He will then push the controlling-lever into the running position after the motor has become a generator and, break the circuit through the shunt-winding of the electromagnet. In this wa will be avoided the application of the bra e when the current .in the armature changes direction, due to the motor becoming a generator in the first inv stance; but thereafter the brake will be ap plied whenever the" generator again becomes a motor or the current sent through the series winding of the magnet falls to so small an amount as to reduce the pull of the magnet below that required to hold the brake in an inoperative osition.

Many mo ifications of the. manner of completin the electrical circuits and in the use of di erently-wound motors will suggest themselves which will contain the spirit of my invention, I having herein described and shown but one of the many uses-in which a compound-wound 'electromagnet maybe employed for brake-operating purposes.

What I claim is 1. Thecombination .with a',source of ourrent-supply, a motor electrically connected therewit a fpulley operated by said motor, a

or said pulley, a lever for operating said brake-band and a weight connected to said lover, of a compound-wound electroma et having its core arranged to lift the saidweight to release the said brake- :band, and one of its energizing-coils connected in serieswith the "armature of said motor and its other energizing-coil connected directly across the current-supply line, and means for swltching the current so as to energize theshunt-coil of said magnet rior a ulleyoperated by said motor, a I brake-band or said pulley, a lever for opera't-f rec 75 app led and the apparatus retarded, so that ing said brake-band and a weight connected to said lever, of a compound-wound electroma net having its core arranged to lift the sai weight to release the said brake-band, and one of its energizing-coils connected in series with the armature of said motor and its other energizing-coil connected directly across the current-supply line, and means for energizing said shunt-coil prior to closing thel circuit to the armature and said series 001 3. The combination with a source of current-supply and a motor electrically connected therewith, of a brake tending normally to prevent the rotation of the armature of said motor, and a compound-wound electromagnet having its core connected with said brake and adapted to release the brake to permit the rotation of the armature-shaft, said electromagnet having one of its energizing-coils in series with the armature of the motor and its other energizing-coil connected directly across the current-Suppl line, and means for energizing said latter 0011 prior to closing the circuit to the armature and prior to closing the circuit through said series coil of the electromagnet.

4. The combination with a source of current-supply and a motor electrically connected therewith, of a brake tending normally to prevent the rotation of the armature of said motor, and a compound-wound electromagnet having its core connected with said brake and adapted to release the brake to permit the rotation of the armature-shaft, said electromagnet having one of its energizing-coils in series with the armature of the motor and its other energizing-coil connected directly across the current-suppliy line, and a currentswitching mechanism a apted to connect the said shunt-coil of the electrical circuit with said source of current-sup ly prior to connecting either the series coil or the armature into said electrical circuit and for cutting out said shunt-coil after the brake has been released and after the motor has been started, whereby the brake is maintained in ino rative position by means of said series 0011 energizing the said magnet.

5. The combination with a source of current-sup ly, a motor electrically connected therewit and a brake for controlling the rotation of the armature-shaft of said motor, of a compound-Wound electromagnet for operating said brake, said electromagnet having both its series and its shunt coil connected in the electrical circuit between said source of current-supply and said motor, a currentswitching mechanism having the switchinglever 18, the series ofcontacts 18for controlling the current to the armature on said motor and to the series coil of said magnet, and the switching-contact 31 for controlling the flow of current to said shunt-coil of said magnet.

6. The combination with a rotatable shaft, means for rotating said shaft and a brake for controllin the rotation of said shaft, of a compoun -wound electromagnet connected into an electrical circuit and having its shuntcoil adapted to release the said brake to permit the rotation of said shaft and its series coil arranged to maintain the brake in in-' operative position as long as the current flowing in the circuit exceeds a predetermined amount.

7. The combination with a rotatable shaft, means for rotating said shaft, and a brake for controllin the rotation of said shaft, of a compoun ,-wound electromagnet arranged to be connected into an electrical circuit and having a shunt-coil adapted to release the said brake to permit the rotation of said shaft and a series coil adapted to maintain the brake in its inoperative position after it has been released and as long as the electromotive force of the circuit exceeds a predetermined amount, and means for first connecting said shunt-coil into the electrical circuit and then connecting said series coil into the electrical circuit.

' In testimony whereof I afiix my signature in presence of two witnesses.

FRANK L. SESSIONS. 

